Not sure but I am able to open through IE

Actually Windows' resolver is known to simply drop illegal characters off the end of a host name if it helps to resolve it.

This is wired output but as Era stated I could believe it:

From Unix box:

11> telnet nyustern-.collegemailer.com 80
telnet: nyustern-.collegemailer.com: Name or service not known
nyustern-.collegemailer.com: Unknown host

12> telnet nyustern.collegemailer.com 80
Trying 209.200.118.155...
Connected to nyustern.collegemailer.com.

From DOS command window:

C:\>telnet nyustern-.collegemailer.com 80


GET / HTTP/1.0
Host: nyustern-.collegemailer.com

HTTP/1.1 302 Object moved
Connection: close

But my issue is how can I resolve this at code level - what I need to do in such a case?

You can probably approximate what Microsoft is doing by simply dropping any illegal trailing characters.

By the by, the highlighted Server: header is a red herring; the issue is with how a Windows client would resolve the domain name.

If you can run tcpdump on the DNS traffic from the Windows box while it resolves and visits the site in IE (or simply opens a telnet session), you should see what host name the Windows box is actually resolving.

I tried ways to dump tcp packets in windows and Unix but unfortunately unable to succeed cause I have a windows network login and ssh to unix development servers as developer.

Is there any other way I can do away with findings?

You don't have any way to get access to a local Windows box? Lucky bastard. (-:

I believe there are VMware Player images with preinstalled Windows images you could play around with. Install Ethereal and watch it resolve. DNS is UDP port 53.